Percussion tools having a reciprocable hammer piston actuated by combustion gases



G. B. WAHLSTEN ETAL 2,764,138 PERCUSSION TOOLS HAVING A RECIPROCABLE HAMMER PISTON ACTUATED BY COMBUSTION GASES 5 Sheets-Sheet 1 Sept. 25, 1956 Filed March 2, 1954 Fig.

Fig.3

p 25, 1956 G L. B WAHLSTEN ETAL 2,764,138

PERCUSSION TOOLS HAVING A RECIPROCABLE HAMMER PISTON ACTUATED BY COMBUSTION GASES Filed March? 1954 5 Sheets-Sheet 2 Fig. 2

W 25, 1956 G. 1.. B. WAHLSTEN ETAL 2,764,133

PERCUSSION TQOLS HAVING A RECIPROCABLE HAMMER PISTON ACTUATED BY COMBUSTION GASES Filed March 2, 1954 3 Shee ts-Sheet 5 w m y United States Patent f PERCUSSION TOOLS HAVING A RECIPROCABLE IILiggS/[ER PISTON ACTUATED BY COMBUSTION Giista Ludvig Bertii Wahlsten, Stockholm, and Bengt Vlktor Nyholnl, Saltsjo-Bo, Sweden, assignors to Atlas gopgo Aktiebolaget, Nacka, Sweden, a corporation of we en Application March 2, 1954, Serial No. 413,598 Claims priority, application Sweden March 2, 1953 9 Claims. (Cl. 123-7) This invention relates to improvements in percussion tools having a reciprocable hammer piston actuated by combustion gases for producing the percussion stroke and by pressure gas or air in a chamber in the tool for producmg the return stroke of the hammer piston and provided with automatic power means for rotating a drill steel. The invention is principally characterized by the provision in the tool of means for simultaneously making said drill steel rotating means and said return stroke producing means inoperative to rotate the drill steel and to produce the return stroke, respectively. Tools of this type usually include a combustion motor portion working on the two-stroke cycle principle. When such a motor has been started it is often desirable to keep it running during the time when the tool is in operation. One object of the invention is to facilitate starting of the combustion motor portion and starting of the drill hole and to prevent accidents, this being achieved according to the invention by the provision of a tool in which the motor portion may be started at no load and with the drill steel turning mechanism disconnected and in which the setting of the tool from drilling to idle running motor portion simultaneously causes the drill steel rotation to cease.

In the accompanying drawings one embodiment of a percussion tool according to the invention is illustrated by way of example it being understood, however, that various modifications of the invention may be made Within the scope of the claims. Fig. l is a longitudinal section of the tool on a plane including the crank shaft of a combustion gas driven percussion tool in which the motor portion includes a motor piston connected to a crank shaft and a free opposed motion hammer piston. Fig. 2 is a longitudinal section of the tool on a plane perpendicular to the crank shaft. Fig. 3 is a detail section of one end of the crank shaft and cooperating means for transmitting motion to a drill steel rotation mechanism. Fig. 4 illustrates on a larger scale a lower casing forming a part of the tool containing means for engaging and disengaging the drill steel rotation mechanism. Fig. 5 is a view substantially on line V-V in Fig. 4, and Figs. 6, 7 and 8 are cross sections on line VI-VI in Fig. 5 showing a disengaging and valve member in various positions.

I The percussion tool illustrated on the drawings cornprises a crank case, 1, 2 in which a crank shaft 3 is journalled for rotation and which has two handles 4, 5 provided thereon. The tool also comprises a compressor cylinder 6, a motor cylinder 7 provided with cooling fins and a lower casing 8. The crank case carries a fuel tank 9 and the crank shaft carries a flywheel 10 provided with a rope starter drum 11 for starting of the tool, a magneto 12 for generating ignition current, and a cooling fan 13 operating in a spiral casing 14 formed in one of the crank case portions. A connecting rod 15 is journalled on the crank pin of the crank shaft 3 and connected by means of a piston pin 16 to a dilferential trunk piston. Said piston consists of a motor portion 17, a sleeve portion 18, and a compressor portion 19. The motor portion 17 in conventional manner controls openings in the cylinder 7 2,764,138 Patented Sept. 25, 1956 through which scavenging air and fuel is supplied to the combustion chamber of the motor cylinder through passages 20 leading to the combustion chamber from the crank case. scavenging air is drawn into the crank case and compressed therein by the combined motor and compressor piston 17, 19. Fuel is supplied to the scavenging air from a fuel tank 9 by means of a carburetter (not illustrated) in conventional manner. 21 indicates a spark plug and 22 an exhaust manifold. 23 is a sealing ring provided between the combustion and compressor cylinders and forming a seal with the sleeve portion 18 of the differential piston.

The compressor portion 19 draws air through an opening controlled by a valve 24 into the annular compressor chamber 25 and compresses the air therein and delivers it over valve 26 through a conduit 27 to a chamber 28 in the lower casing 8. A hammer piston formed as a differential piston is free to reciprocate in the cylinder 7 and an auxiliary cylinder 29 with larger diameter extending into the lower casing 8. The hammer piston consists of a portion 30 with small diameter and a portion 31 with large diameter. The portion 3t operates in the motor cylinder and the portion 31 in the auxiliary cylinder 29. Air compressed by the compressor portion 19 in the chamber 25 flows from the chamber 28 through openings 32 into an annular space 33 on the upper side of the hammer piston portion 31 and through openings 34 into a chamber 35 in the auxiliary cylinder 29 confined by the lower face of the piston portion 31 and cylinder cover 36 forming the lower head or bottom of the chamber 35. The cover 36 provides guiding means for an anvil block 37 and also confines a chamber 38 in the lower casing accommodating the drill steel turning mechanism. A drill steel chuck 39 is rotatably journalled in the lower casing 8 which also carries a drill steel retainer 40, swingably mounted on the casing 8 as is obvious from Fig. 2, and capable of retaining a drill steel 41 or other working implement. The drill steel chuck may be provided with interlocking means, such as a transverse pin inserted in the lower casing and entering a corresponding hole in thechuck so that turning of the chuck may be prevented when it is desired to use the tool as a concrete breaker, or as a spade tool, or the like.

The openings 32 and 34 serve to admit compressed air into the chambers 33 and 35 as aforesaid. The air cushion in the chamber 33 prevents the hammer piston from hitting the upper end wall of the annular chamber 33 with the annular piston portion 31. A passage 42, 43 leads from the chamber 28 to the chamber 38, said passage being controlled by an adjusting screw 44. From the chamber 38 passages 45 in the anvil block 37 lead to a conventional flushing passage (not illustrated) in the drill steel 41. A packing 46 prevents flushing air in the chamber 38 from leaking to the atmosphere between the shank of the drill steel 41 and the drill chuck 39.

In order to make possible turning of the drill steel it the chuck 39 forms a ratchet wheel 47 provided Wlill teeth cooperating with a pawl 53 operated to rotate the ratchet wheel 47 in a certain direction. For this purpose the pawl 48 is hingedly connected to an arm 49 provided on a shaft 5t which oscillates during the operation of the tool. A spring 51, Fig. 5, normally keeps the pawl 48 in a position in which it engages the ratchet wheel The oscillating turning movement of the shaft 53 1s derived from the crank shaft 3 which for this purpose has a pin 52 at one end set at an angle with respect to the longitudinal rotation axis of the shaft 3, as is obvious from Figs. 1 and 3. A block 53 is mounted on said pin 52 and said block is slidable in the forked end 54 of the oscillatable shaft 56. When the crank shaft 3 turns one revolution this well known motion transmission causes the shaft 50 and arm 49 to produce an oscillating turning 3 movement which causes the pawl 48 to reciprocate and to turn the ratchet wheel 47 and the drill steel chuck 39 thereby turning the drill steel.

A disengaging and valve member 55 is rotatably and axially displaceably mounted in the lower casing 8. The member 55 may be said to be a combined sleeve valve and disengaging means for the pawl 43. The member 55 is provided with a handle 56 accessible from the outside of the lower casing 3 so that the member 55 may easily be turned. A spring loaded ball lock 57 cooperates with a number of notches 58 in the member '5 to retain said member in various positions of adjustment. The member 55 forms a seal in the lower casing 8 and is provided at its inner end with an arm or finger 59 ending with a head 60 having a disc-like shape as indicated in chain dotted lines in Figs. 6, 7 and 8 and arranged in such a manner that the head in the position of the member 55 illustrated in Figs. 4, 5 and 6 leaves the pawl 48 free to move for turning the ratchet wheel 47. The member 55 is provided with a cam groove 61 cooperating with a lug 62 formed on a screw 63 in such a manner that the member 55 when turning by means of the handle 56 is displaced axially. Two passages 64, '65 are provided in the lower casing 3 and lead, as is obvious from Fig. 4, from the chamber 35 to the atmosphere said passages being controlled by the member 55. The member 55 has a transverse passage 66 and an axial peripheral groove 67 extending from the inner end of the sleeve portion of the member in the peripheral portion thereon.

The member 55 operates in the following manner: When the percussion tool is operated as a rock drill and is started the handle 56 is at first turned 90 from the position illustrated in Figs. 46 causing the member 55 to take the position illustrated in Fig. 7. During this turning motion the member 55 is axially displaced so that the head 6% pulls the pawl 43 out of engagement with the ratchet wheel 4'7. Consequently, no turning of the drill steel chuck can be produced when the crank shaft starts to rotate. Simultaneously, the passage 66 connects the passages 64 and 65 so that the chamber 35 is vented to the atmosphere. Consequently, the hammer piston 3t 31 remains in bottom end position. By means of a starter rope (not illustrated) the starter rope drum ii is rotated and the motor portion of the tool is started and the tool runs idle. No percussion work is then produced since the hammer piston so, 31 never lifts from its bottom positron. As soon as the motor portion is running and the operator is ready to start drilling he places the tool with the steel 41 against the spot to be drilled and turns the handle 56 90 in reverse direction to the position illus trated in Figs. 4, 5 and 6 causing the venting passage from the chamber 35 to be closed and the pawl 48 to be moved into engagement with the ratchet wheel 7 by the spring 51. The weight of the tool causes the shank of the steel 41 to lift the anvil block 3'7 to the position in Figs. 1 and 2. The compressed air produced by the compressor portion 19 in the chamber 25 and supplied through the conduit 27 to the chamber 28 and admitted through the openings 34 to the chamber 35 lifts the hammer piston 3d, 31 which starts to operate and to cooperate with the motor piston 17. Compressed air simultaneously admitted through the openings 32 to the annular chamber 33'; provides an air cushion in said chamber. The tool now operates as a rock driil with air flushing of the drill hole.

if it is desired to use the tool as a concrete breaker or as spading tool or the like in which case rotation of the working implement is not desired or permitted the drill steel 41 is replaced by a chisel or other implement which is inserted in the drill chuck 39. Starting of the tool is made after turning of the handle 56 so that the member 55 takes the position illustrated in Fig. 7. The motor portion is then started in the manner above described and the tool runs idle. When the motor portion has started the handle 56 is turned 90 to the position illustrated in Fig. 8. in this position the venting of the chamber 35 is interrupted but the pawl 48 is still kept in inoperative position. Through the groove 67 which is now connected with its inner end to the opening 65 venting of the chamber 38 is obtained so that supply of flushing air is interrupted. The shank of the implement lifts the anvil block in the same way as in drilling and the hammer piston 39, 31 now operates and reciprocates and delivers impacts to the tool implement but without turning the implement, i. e. the tool operates as a concrete breaker, a spade tool, or the like.

The tool above described and illustrated in the drawings should only be considered as an example and the details of the tool may be varied in various different ways within the scope of the claims. The invention may for instance be employed in combustion gas driven tools in which the rotation of the drill steel is obtained in some other way than by means transmitting motion from the crank shaft, for instance in tools in which the drill steel rotation is obtained or derived from the reciprocation of the hammer piston which for this purpose may be provided with suitable straight and inclined splines cooperating with a pawl and ratchet mechanism of a type well known in connection with rock drills.

What we claim is:

1. In a percussion tool, a combustion cylinder forming part of said tool, a hammer piston reciprocable in the tool, a portion of said hammer piston actuated by combustion gases in said combustion cylinder to produce the percussion stroke of the hammer piston, means for actuating the hammer piston to produce the return stroke of the hammer piston, a drill steel chuck rotatably mounted in the tool, power means in the tool independent of the hammer piston for rotating said chuck, and means for simultaneously making said actuating means and said power means inoperative to produce said return stroke and to rotate said chuck, respectively.

2. In a percussion tool, a combustion cylinder forming a part of said tool, a hammer piston reciprocable in the tool, a portion of said hammer piston actuated by combustion gases in said combustion cylinder to produce the percussion stroke of the hammer piston, means for actuating the hammer piston to produce the return stroke of the hammer piston, a drill steel chuck rotatably mounted in the tool, power means for rotating said chuck, a manually operable control member in the tool having two positions of adjustment, a first means on said member for making said actuating means inoperative to produce said return stroke upon displacement of the member from one of said positions to the other, and a second means on the member for making said power means inoperative to rotate said chuck upon said displacement of the member from said one position to the other.

3. In a percussion tool, a combustion cylinder forming a part of said tool, a hammer piston reciprocable in the tool, a portion of said hammer piston actuated by combustion gases in said combustion cylinder to produce the percussion stroke of the hammer piston, means for actuating the hammer piston to produce the return stroke of the hammer piston, a drill steel chuck rotatably mounted in the tool, power means for rotating said chuck, and associated means for simultaneously making said actuating means and said rotating means inoperative to produce said return stroke and to rotate said chuck, respectively, upon movement of said associated means into one position and for making the actuating means operative and the rotating means inoperative upon movement into another position.

4. In a percussion tool, a combustion cylinder forming a part of said tool, an auxiliary cylinder forming a part of the tool, a hammer piston reciprocable in said auxiliary cylinder, a portion of said hammer piston actuated by combustion gases in said combustion cylinder to produce the percussion stroke of the hammer piston, a second portion of the hammer piston actuated by an elastic pressure fluid in a chamber in the auxiliary cylinder to produce the return stroke of the hammer piston, a drill steel chuck rotatably mounted in the tool, a power driven pawl and ratchet mechanism in the tool capable of rotating said chuck, a passage in the tool communicating with said chamber, and a valve member in said passage capable upon displacement into a certain position of interruption of the action of said elastic pressure fluid to produce the return stroke of the hammer piston and of disengaging said pawl and ratchet mechanism to interrupt rotation of the chuck.

5. In a percussion tool, a combustion cylinder forming a part of said tool, an air compression cylinder forming a part of the tool, a combined motor and air compressing piston reciprocable in said cylinders, a crank mechanism in the tool operably connected with said motor and air compressing piston to be driven by said piston, an auxiliary cylinder forming a part of the tool, means for feeding pressure air compressed by the air compressing piston into a chamber in said auxiliary cylinder, a hammer piston reciprocable in the auxiliary cylinder and acted upon by said pressure air in the auxiliary cylinder for producing the return stroke of the hammer piston, a drill steel chuck rotatably mounted in the tool, a pawl and ratchet mechanism in the tool driven from said crank mechanism and capable of rotating said chuck, a vent passage in the tool communicating with said chamber in the auxiliary cylinder, and a valve member in said passage capable upon displacement into a venting position to cause interruption of the action of the pressure air to produce return strokes of the hammer piston and simultaneously to make said pawl and ratchet mechanism inoperative to rotate the chuck.

6. Apparatus as defined in claim 5, in which a chamber is provided in the tool in communication with a flushing air duct to the drill steel, means for supplying pressure air to said chamber, and means in said valve member capable upon displacement into said venting position to cause venting of the flushing air from the chamber.

7. Apparatus as defined in claim 5, in which the auxiliary cylinder is disposed in a lower casing in the tool and the valve member consists of a sleeve rotatably and axially displaceably mounted in said lower casing, a handle on said sleeve accessible at the outside of the lower casing, cam means on the sleeve and lower casing cooperating to produce axial displacement of the sleeve upon turning of the sleeve with said handle through a certain angle, a ratchet wheel forming a part of the pawl and ratchet mechanism and rotatably mounted in the lower casing for rotating a drill steel, an oscillatable shaft driven by the crank mechanism and extending into the lower casing and operably connected to the pawl, and a finger on the sleeve operable to disengage the pawl from the ratchet wheel upon axial displacement of the sleeve.

8. In a percussion tool, a cylinder casing in said tool, a combustion cylinder in said cylinder casing, a compressor cylinder with larger diameter than said combustion cylinder in the cylinder casing, said cylinder casing being divided perpendicularly to the casing axis adjacent the portion where the large diameter compressor cylinder merges into the small diameter combustion cylinder, a piston having a motor portion and a compressor portion reciprocable in said combustion and compressor cylinders respectively, a crank shaft mounted in the tool and connected with said motor and compressor piston, an auxiliary cylinder in the cylinder casing, a differential hammer piston reciprocable in the combustion cylinder and said auxiliary cylinder and actuated by combustion gases in the combustion cylinder to produce the percussion stroke of the hammer piston, and a communication between the compressor cylinder and the auxiliary cylinder for supplying pressure air to the auxiliary cylinder to actuate the hammer piston to produce the return stroke.

9. A percussion tool according to claim 8, in which a sealing ring is provided in a groove in the cylinder casing adjacent the portion where the cylinder casing is divided, said sealing ring having an internal sealing surface engaging and forming a seal with the external surface of the motor portion.

No references cited. 

